District Judge James D. Peterson entered an opinion and order on November 6, 2026, in Delkor Systems, Inc. v. Pratt Industries, Inc., No. 3:25-cv-00306 (W.D. Wis.), Dkt. 100. The defendants are Pratt Industries, Inc., Pratt Retail Specialties, LLC, and Pratt (Beloit Corrugating), LLC. The case was filed April 18, 2025. The opinion says Delkor is a Minnesota corporation that makes packaging equipment, and that Pratt, the name the opinion uses for the three defendants together, is a Wisconsin corporation that also makes packaging equipment.
The patents and the accused package
Delkor asserts U.S. Patent 9,555,919 and U.S. Patent 10,421,580, both titled "Convertible Package Assembly and Display System." The '919 patent issued January 31, 2017, and the '580 patent issued September 24, 2019. The opinion says the '580 patent is a continuation of the '919 patent. The accused product is a corrugated cardboard package for shipping and displaying frozen pizzas. Delkor asserts claim 1 of the '919 patent and claims 5 and 7 of the '580 patent. Pratt did not contest validity on summary judgment.
Single tear line
The court held that "single tear line" requires "a continuous physical tearing mechanism that extends through the case blank." It found that the accused product has a handhold separating two perforated tear lines, so the product does not literally infringe. The court did not reach the "fifteen polygonal sections" limitation.
The opinion says the Delkor patents incorporate by reference U.S. Patent 5,657,872, which discloses a packaging assembly with a removable portion and a cut-out handhold. The court concluded that the incorporated patent does not support Delkor's construction, because it does not describe the line of weakness as continuous.
The court also rejected infringement under the doctrine of equivalents. It wrote that "[n]o reasonable jury could find that the accused product is an equivalent of the patented product" when, in the court's words, Delkor's own expert "admits that there is a difference in function related to a key feature of the patented product."
The judgment
The order grants Pratt's motion for summary judgment of non-infringement, Dkt. 78, denies Delkor's motion for partial summary judgment on infringement, Dkt. 74, and directs the clerk to enter judgment for the defendants and close the case. Judgment was entered the same day.
What to watch next
Watch whether Delkor files a notice of appeal. Under Federal Rule of Appellate Procedure 4(a)(1)(A), a notice of appeal is due 30 days after entry of the judgment.